It is known to produce a container provided with a body and a generally planar annular flange integral with the body, and in particular a yoghurt pot or similar, by means thermoforming a sheet of plastic to form the volume. Typically, the plastic sheet is heated and then drawn into a cavity such as by vacuum and/or pressure. As the sheet is drawn into the cavity, the thickness of the portion of the sheet drawn into the cavity is reduced as the sheet material is stretched into the cavity. With such a method, the side wall of the body is thin, while the flange has the same thickness and the same rigidity as the original sheet of plastic. As the flange is thin and planar, the body essentially defines the height of the container.
Regarding the forming of the body, the thickness of the sheet material can be reduced when increasing the depth of the cavity. It can be appreciated that problems may occur where the plastic material rapidly changes angles in the volume such as at the bottom and sidewall of a cup-shaped container. It is thus not recommended having a too thin side wall for the purpose of sustaining the rigors of distribution.
The plastic containers are conventionally sealed with membranes and can be manufactured and sold in a multiple portion packaging tray comprising an array of separable containers. After separation, each container flange still has four outer side edges so as to keep integrity of the content. These containers work well when made of relatively brittle plastic. Use of less brittle or more pliable polymers makes the containers more difficult to break apart. Such a difficulty may cause escape of the content when breaking other parts of the container.
In food packaging industry, the plastic containers can be stacked on top of one another so as to form stacks which can be layered on a pallet. A loading weight on a pallet may be much more than 500 kg. Such stacks allow the packaging items at the bottom to withstand the compressive load of the packaging items on top. The plastic containers layers are typically stored in cardboard trays each having a bottom and side walls preventing lateral tilting of the layers.
There are already some solutions to provide to the consumers containers with less plastic material. For instance, the French patent FR 2 432 975 describes plastic containers with polygonal flanges, V-cuts being provided to recycle material of the flanges.
However, the weight of the plastic containers cannot be easily reduced since the containers made of relatively brittle plastic have to be transported in a safe manner and without any deformation. The packs of containers have to be sufficiently robust in particular for transportation on a pallet. It is also preferably required that the containers are user-friendly, i.e. not complicating user's operations such as separating an individual container, opening the membrane seal, eating the content.
The plastic containers of this type are typically produced in very large quantities and may be each covered by a decorative strip or band (also called banderol). Decorative strips are very commonly used for packagings containing dairy products such as for example yoghurts or butter but also products such as stewed fruit or margarine. Such a decorative strip is aesthetically advantageous and may contain a lot of useful information. Moreover such a decorative strip contributes to strengthening the container. In order to reduce the total weight of the packaging, a need exists for reducing the amount of material in the decorative strip. More generally, it is important as far as possible to reduce the unit cost of each packaging but without impairing its strength and its aesthetic characteristics.
Containers having a lower portion tapering toward the bottom in a curved manner are believed to have a visually distinctive shape that is appreciated by consumers. However such lower portions provide a low resistance to top compression and some deformation can occur. There is a need for containers that have a curved lower portion with an improved resistance and/or with a reduced amount of material.